The influence of partial peening of fatigue crack growth

Fatigue crack growth rate is an important factor for the life assessment of engineering components and structures. Various surface treatment techniques have previously been developed and employed in industrial applications to extend the fatigue life of engineering structures by implementing compressive residual stresses on material surfaces. Residual stresses can decelerate or accelerate fatigue crack growth in engineering structures, depending on their distribution profiles (i.e. tension or compression). In this thesis, the influence of partial surface peening on the fatigue crack growth of a high strength steel (HSS) material has been investigated by performing laboratory tests. The effects of partial peening on the fatigue crack growth behaviour of Optim700QL ferritic HSS have been experimentally investigated. Dog-bone shaped specimens were tested under tension-tension fatigue load and specimens with semi-circular notches were tested under 4-point bending conditions. An initial notch was machined in the middlewidth of all specimens to create a starter crack for fracture mechanics studies. Three distinct extents of partial shot peening and cavitation shotless peening, with respect to the crack tip and specimen symmetry line, were applied on the specimen geometry. The finite element modelling (FEM) was used to first calculate the shape function, and then the stress intensity factor (SIF), to develop a new model for 4-point bend specimen geometry with the dimensions considered in this project, the solutions of which are not available in the literature. Moreover, FEM was used to predict the stress concentration factor (SCF) for a dog-bone specimen to avoid reaching plasticity at the crack tip in load calculations for tension-tension tests. The fatigue crack growth results from the partially peened specimens have been compared with those obtained from similar specimen geometry but with no peening. The results show that the residual stress fields formed ahead of the initial notch tip due to the peening process play a significant role in the fatigue crack growth behaviour of the material, indicating that partial surface peening can be used as an effective method to decrease the fatigue crack growth rate under pure bending fatigue loading conditions, but is harmful under tension-tension loading conditions

Turbulent Flow Simulations

This chapter consists of four sections; Introduction, Boundary and initial conditions, Setting of nonuniformly spaced grid, and Simulation approach. The fields of the fluctuating velocity describe the turbulent flows. Such fluctuations blend the transported quantities, like species concentration, energy, and momentum and make the transported quantity fluctuations in addition. Because such fluctuations have a small scale and high frequency, so they are very computationally costly for simulation straightforward in the virtual engineering computations. Alternatively, the instantaneous accurate governing equations can be time-averaged, ensemble-averaged, or in different way handled for removing the small scales, causing a modified group of equations, which are computationally less costly for solving

Performance improvement for mobile ad hoc cognitive packets network

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonIn this thesis, focusing on the quality of service (QoS) improvement using per-packet power control algorithm in Ad Hoc Cognitive Packet Networks (AHCPN). A power control mechanism creates as a network-assisted function of ad hoc cognitive packet-based routing and aims at reducing both energy consumption in nodes and QoS requirements. The suggested models facilitate transmission power adjustments while also taking into account the effects on network performance. The thesis concentrate on three main contributions. Firstly, a power control algorithm, namely the adaptive Distributed Power management algorithm (DISPOW) was adopted. Performance of DISPOW was compared to existing mechanisms and the results showed 27, 13, 9, and 40 percent improvements in terms of Delay, Throughput, Packet Loss, and Energy Consumption respectively. Secondly, the DISPOW algorithm was enhanced, namely a Link Expiration Time Aware Distributed Power management algorithm (LETPOW). This approach periodically checks connectivity, transmission power, interference level, routing overhead and Node Mobility in AHCPN. The results show that LETPOW algorithm improves the performance of system. Results show further improvement from DISPOW by 30,25,30,42 percent in terms of delay, packet loss ratio , path lengths and energy consumption respectively. Finally,Hybrid Power Control Algorithm (HLPCA) has presented is a combination of Link Expiration Time Aware Distributed Power management algorithm (LETPOW) and Load Power Control Algorithm (LOADPOW); deal with cross-layer power control applied for transmitting information across the various intermediate layers. LOADPOW emphasis on the concept of transmission Power, Received Signal Strength Indication (RSSI), and the suitable distance between the receiver and the sender. The proposed algorithm outperforms DISPOW and LETPOW by 31,15,35,34,44 percent in terms of Delay, Throughput, Packet Loss,path length and Energy Consumption respectively. From this work, it can be concluded that optimized power control algorithm applied to Ad-hoc cognitive packet network results in significant improvement in terms of energy consumption and QoS

PRESSURE EQUALIZING MANIFOLD FOR ATOMIZED SPRAY BARS

In view of the limitations of existing systems, described herein is a manifold for equalizing pressure/flow throughout a full length of cooling bars and nozzles (such as but not limited to atomizing spray bars). The manifold may reduce the traditional multiple connections (e.g., one connection per nozzle) down to one connection per manifold. The manifold described herein may provide improved reliability and maintainability, thereby providing savings in costs and downtime

Engineering and Minerological Characteristics of Sand Dunes of Babylon Governorate, Iraq

The engineering and mierological of sand dunes has been investigated in this paper. The engineering characteristics study involved studying the dimensions of the dunes, their slope angles, analyzing the curvature of their surfaces and sieve analysis. The mierological characteristics included XRD, XRF, and Thin section for specimens. The investigated area involved three differnts zones lie in the Babylon Governorate in the cnter of Iraq. The zones are called Ramlet Rashid, Ramlet Albu Faris and Birmana area. It has a desert environment, which is characterized by little rainfall, ranging from 50 to 200 mm annually, and high summer temperatures that can exceed 50°C, with northwest winds dominating. The grain size distribution of the sand was found to be 99% in an engineering study of sand dune soils. According to USCS, the sand is of the type (Sp), which is sandy badly graded. The bulk density of sand dune soils for the study area locations ranged from 1.287 to 1.376 g /cm3, The lowest concentration was 1.287 g/cm3 in the Bermana area (third site), while the highest concentration was 1.376 g/cm3 at the Ramlet Rashid site (first site), with an average of 1.3315 g/cm3. The internal friction angle (Ø) for sand dune soils for the research area sites ranged from 33 to 34 in the direct shear test, with the minimum being 33 in Ramlet Rashid and the maximum being 34 in Albu Faris. Having a 33.5 percent rate The convergence of the internal friction angle (Ø) values for sand dunes reflects the deposition environment as well as the geometric characteristics of the sand dunes, Because the soil is SP without cohesion and clays, the cohesion (C) values for all sites are (0). The petrographic investigation of sand rise soils uncovered that quartz is the most light mineral tracked down in all areas, trailed by rock pieces, which include: sedimentary rocks (calcareous rocks, carbonates, chert, evaporites, and earth rock sections), trailed by feldspar (antacid and plagioclase feldspar), and volcanic stone parts, transformative shakes and mud-covered grains. Concerning its weighty minerals parts, for the most part hazy minerals, the chlorite bunch, the mica bunch, the amphibole bunch, the pyroxene bunch, zircon, termolite, garnet, rhyolite, staurolite, kainite, rutile, and different minerals by 1%. X-Ray diffraction test uncovered the presence of quartz, albite and calcite, and X-Ray fluorescence tests showed the presence of silica (SiO2) and lime (CaO)

Prevalence and diagnostic significance of de-novo 12-lead ECG changes after COVID-19 infection in elite soccer players.

BACKGROUND AND AIM: The efficacy of pre-COVID-19 and post-COVID-19 infection 12-lead ECGs for identifying athletes with myopericarditis has never been reported. We aimed to assess the prevalence and significance of de-novo ECG changes following COVID-19 infection. METHODS: In this multicentre observational study, between March 2020 and May 2022, we evaluated consecutive athletes with COVID-19 infection. Athletes exhibiting de-novo ECG changes underwent cardiovascular magnetic resonance (CMR) scans. One club mandated CMR scans for all players (n=30) following COVID-19 infection, despite the absence of cardiac symptoms or de-novo ECG changes. RESULTS: 511 soccer players (median age 21 years, IQR 18-26 years) were included. 17 (3%) athletes demonstrated de-novo ECG changes, which included reduction in T-wave amplitude in the inferior and lateral leads (n=5), inferior leads (n=4) and lateral leads (n=4); inferior T-wave inversion (n=7); and ST-segment depression (n=2). 15 (88%) athletes with de-novo ECG changes revealed evidence of inflammatory cardiac sequelae. All 30 athletes who underwent a mandatory CMR scan had normal findings. Athletes revealing de-novo ECG changes had a higher prevalence of cardiac symptoms (71% vs 12%, p<0.0001) and longer median symptom duration (5 days, IQR 3-10) compared with athletes without de-novo ECG changes (2 days, IQR 1-3, p<0.001). Among athletes without cardiac symptoms, the additional yield of de-novo ECG changes to detect cardiac inflammation was 20%. CONCLUSIONS: 3% of athletes demonstrated de-novo ECG changes post COVID-19 infection, of which 88% were diagnosed with cardiac inflammation. Most affected athletes exhibited cardiac symptoms; however, de-novo ECG changes contributed to a diagnosis of cardiac inflammation in 20% of athletes without cardiac symptoms

Prevalence and diagnostic significance of de-novo 12-lead ECG changes after COVID-19 infection in elite soccer players.

Background and aim: The efficacy of pre-COVID-19 and post-COVID-19 infection 12-lead ECGs for identifying athletes with myopericarditis has never been reported. We aimed to assess the prevalence and significance of de-novo ECG changes following COVID-19 infection. Methods: In this multicentre observational study, between March 2020 and May 2022, we evaluated consecutive athletes with COVID-19 infection. Athletes exhibiting de-novo ECG changes underwent cardiovascular magnetic resonance (CMR) scans. One club mandated CMR scans for all players (n=30) following COVID-19 infection, despite the absence of cardiac symptoms or de-novo ECG changes. Results: 511 soccer players (median age 21 years, IQR 18-26 years) were included. 17 (3%) athletes demonstrated de-novo ECG changes, which included reduction in T-wave amplitude in the inferior and lateral leads (n=5), inferior leads (n=4) and lateral leads (n=4); inferior T-wave inversion (n=7); and ST-segment depression (n=2). 15 (88%) athletes with de-novo ECG changes revealed evidence of inflammatory cardiac sequelae. All 30 athletes who underwent a mandatory CMR scan had normal findings. Athletes revealing de-novo ECG changes had a higher prevalence of cardiac symptoms (71% vs 12%, p<0.0001) and longer median symptom duration (5 days, IQR 3-10) compared with athletes without de-novo ECG changes (2 days, IQR 1-3, p<0.001). Among athletes without cardiac symptoms, the additional yield of de-novo ECG changes to detect cardiac inflammation was 20%. Conclusions: 3% of athletes demonstrated de-novo ECG changes post COVID-19 infection, of which 88% were diagnosed with cardiac inflammation. Most affected athletes exhibited cardiac symptoms; however, de-novo ECG changes contributed to a diagnosis of cardiac inflammation in 20% of athletes without cardiac symptoms